1. Field of the Invention
The present invention relates to a noise reduction hood for attenuating the level of acoustic noise emanating from an electronic system enclosure.
2. Description of Related Art
An electronic system, such as a computer system, is conventionally comprised of various electronic components, including peripheral devices such as a disk drive, that are mounted and electrically interconnected within an electronic cabinet or enclosure. Electronic components generally are temperature sensitive devices that, if allowed to overheat, are likely to malfunction or become permanently damaged. Since electronic systems can dissipate a large amount of heat, adequate ventilation is critical for removing the heat from the cabinet to avoid creating a high temperature condition that could result in a system failure.
Conventionally, a cabinet is ventilated using one or more fans or blowers to force cooling air through the cabinet so that the temperature of the equipment is maintained within acceptable limits. One problem associated with ventilating electronic cabinets using cooling fans is the emanation of acoustic noise associated with fan operation. Although an individual fan may not produce significant noise levels by itself, electronic cabinets typically utilize multiple fans to produce sufficient air flow through the cabinet. The cumulative affect of multiple fans can produce a level of acoustic noise that poses problems in a work environment. For example, high noise levels can be very distractive and annoying, and can interfere with conversational level speech. This can become even more problematic in office, lab or test area environments where many cabinets of electronic equipment may be operating simultaneously.
A proposed solution to this problem is disclosed in U.S. Pat. No. 5,526,228 to Dickson et al., issued on Jun. 11, 1996. An acoustic dampening shroud is mounted to the rear panel of a computer system enclosure at the cabinet exhaust. The shroud includes acoustic noise reduction lining and a ventilation aperture disposed at the bottom of the shroud, away from the cooling fans, to minimize the amount of noise emanating from the computer system.
Other solutions have been proposed including the use of internal acoustic walls to deflect or absorb noise, or locating the cooling fans toward the center of the cabinet away from the inlet and exhaust apertures.
It is an object of the present invention to provide an improved method and apparatus for reducing the acoustic noise level emanating from an electronic system cabinet.